Department of Genetics, Dartmouth Medical School, Hanover, NH 03755-1404, USA.
J Neurosci. 2012 Mar 28;32(13):4665-74. doi: 10.1523/JNEUROSCI.6178-11.2012.
Detection of specific female pheromones stimulates courtship behavior in Drosophila melanogaster males, but the chemosensory molecules, cells, and mechanisms involved remain poorly understood. Here we show that ppk25, a DEG/ENaC ion channel subunit required for normal male response to females, is expressed at highest levels in a single sexually dimorphic gustatory neuron of most taste hairs on legs and wings, but not in neurons that detect courtship-inhibiting pheromones or food. Synaptic inactivation of ppk25-expressing neurons, or knockdown of ppk25 expression in all gustatory neurons, significantly impairs male response to females, whereas gustatory expression of ppk25 rescues the courtship behavior of ppk25 mutant males. Remarkably, the only other detectable albeit significantly weaker expression of ppk25 occurs in olfactory neurons implicated in modulation of courtship behavior. However, expression of ppk25 in olfactory neurons is not required for male courtship under our experimental conditions. These data show that ppk25 functions specifically in peripheral taste neurons involved in activation of courtship behavior, an unexpected function for this type of channel. Furthermore, our work identifies a small subset of gustatory neurons with an essential role in activation of male courtship behavior, most likely in response to female pheromones.
检测特定的雌性信息素会刺激黑腹果蝇雄蝇的求偶行为，但涉及的化学感觉分子、细胞和机制仍知之甚少。在这里，我们表明，ppk25 是 DEG/ENaC 离子通道亚基，对雄性对雌性的正常反应是必需的，它在大多数腿和翅膀的味觉毛中一个单一的性二态味觉神经元中表达水平最高，但不在检测求偶抑制信息素或食物的神经元中。ppk25 表达神经元的突触失活，或在所有味觉神经元中敲低 ppk25 的表达，显著损害了雄性对雌性的反应，而 ppk25 在味觉神经元中的表达则挽救了 ppk25 突变雄性的求偶行为。值得注意的是，ppk25 的唯一另一种可检测到的表达，尽管明显较弱，发生在与求偶行为调节有关的嗅觉神经元中。然而，在我们的实验条件下，ppk25 在嗅觉神经元中的表达并不是雄性求偶所必需的。这些数据表明，ppk25 在参与激活求偶行为的外周味觉神经元中特异性地起作用，这是这种类型的通道的一个意想不到的功能。此外，我们的工作确定了一小部分味觉神经元在激活雄性求偶行为中起着重要作用，这很可能是对雌性信息素的反应。
